Currently, there exist a number of surgical anastomotic circular staplers. Generally, these staplers are used to connect severed lumen with a circular ring of staples displayed around a circumference to connect the tissue. In most instances, a knife mechanism is used to cut the tissue within the circumference of the staple ring. The ring of staples is generally a number of small metallic surgical staples, usually between 20 and 40 staples, which form a ring roughly 2 cm to 4 cm in diameter. Naturally, with the circular staples there must be minimum constriction of the tissue after healing, and the lumen must be maintained as near as possible as prior to the procedure, to allow normal passage of fluids.
With this type of stapler, there must be a complete 360.degree. seal of tissue so that no gaps exist between the connected tissue. In addition, it is naturally desirable that when the tissue is connected, the volume within which the tissue is cut be maintained so that the tissue is continually able to pass fluids without encountering constricting tissue.
In addition, with such circular anastomotic staplers it is desirable to make staplers which are disposable. That is, disposable staplers are now well accepted by surgeons. Disposable surgical staplers also help prevent the spreading of bacteria or germs. Naturally, the surgeon also desires a manual stapler which gives good off-the-shelf reliability and allows a controlled one-handed operation.
Most importantly, there has been a need for absorbable staplers in the circular fastening market. This is due in part to the prior incapacity to produce a circular anastomotic stapling mechanism where the staples are able to be received within receivers and adequate forces can be generated to hold the tissue together and to clamp the staples. In addition, it is critical in this system to maintain tolerances which enable alignment of staples or fasteners within the receivers. To accomplish this in an absorbable circular anastomotic stapler would increase the likelihood of use of such a stapler within hard to reach or marginally compliant lumen. It is to be realized that typical absorbable fasteners have an enlarged size, preventing use in such places.
Furthermore, it is desirable to replace a standard staple line with two adaptively connectable fasteners. In this way, the need for bending of staples is removed, and yet closure and hemostasis are possible. Of course, by attempting to formulate a system in which a standard staple line is replaced, it would be desirable to formulate such a stapler so that the stapler itself can be pulled through the attached part of the tissue without the need for removing the anvil portion of the stapler. This results in a rapid and efficient method of removing the stapler. In the desire for creating such a adaptively connectable mating fastener, it is naturally desirable that these fasteners are both positively aligned and latching, and that they are formulated so that the instrument creates closure at some constantly adjustable closure pressure. If the pressure required to attach the latching members together remains constant, it is much easier to close and latch the instrument with a smooth, efficient single stroke. Alternately, it may be desirable to rely on the constant closure pressure to attach the fastener through the tissue, and then, in a separate action, actually close the tissue with the instrument.
In such a system it would also be desirable to readily see whether the fasteners are connected and the tissue is adequately closed. This is especially true where the instrument is pulled through the connected tissue. Also, these type connections should be available on all circular-type instruments, including those with curved shafts or instruments containing trocars or flexible shafts.